Thanks for your reply - Sadly though none of these freqs are used for the Tacan route TR1 as far as I'm aware.

By the mere fact they are ICF's they will not be used. In my 38+ years of flying military and the last 18 years on "Heavies" we would never use an ICF unless climbing out of Low Level. It would be an "Internal" frequency handover from one radar unit to another.

Unfortunately in all my flying and being UK based we never used the TR's ... hence the reason I'm asking.

I monitor the ICF freqs whenever I can, and have often heard aircraft routed VLN - BZN - MAM - NAVPI.If it wasn't ICF freqs must have been secondary freqs, I'll pay more attention to which and let you know …SW231.825282.5372.675Central251.475341.675East233.725252.975261.35269.475275.65

I reserve the right to ignore people who have made no attempt to the read the manual, and expect others to do it for them.

Just seen your post so hope you don't mind me commenting a bit later but most aircraft taking TR1 in the South Western corner will be working sector 9 on 132.950 and in an area roughly North/South abeam Bristol get transferred to Swanwick mil central on 252.875 or 128.700 but can be other frequencies such as 278.600 on occasion. From a point roughly abeam Peterborough they work Swanwick mil East on 259.600 or 133.325 (but again, not always!). Further East outside the UK FIR it can sometimes be Maastricht Delta sector on 135.960. The RCH flight on the more Northerly route are usually working Sector 11 on 126.780 and further North, usually Scottish Montrose South on 126.925, hope that helps! It's not an exact science I'm afraid, can depend on time of day/night, controller workload, band boxing of sectors etc.